Spark plug electrodes for internal combustion engines, such as automobile engines, have conventionally been made of an Ni alloy of the type described, for example, in Japanese Patent Publication No. 43897/85, which consists essentially (in weight terms) of 0.2-3% Si, less than 0.5% Mn, one or more selected from the group consisting of 0.2-3% Cr, 0.2-3% Al, and 0.01-1% Y, the remainder being Ni and incidental impurities.
Recently, attempts have been made to produce automobile engines of high efficiency by the use of super chargers, such as turbo chargers, and the adoption of a dual overhead cam shaft system. In such high efficiency engines, the temperature of the combustion chambers in the automobile engine is elevated to a higher level than ever attained and the operating conditions of the spark plug electrodes and their surrounding environment are thus extremely harsh. However, as conventional Ni alloys exhibit poor melting loss resistance despite their excellent high temperature corrosion resistance and oxidation resistance, spark plug electrodes made of such a conventional Ni alloy cannot withstand practical use for long periods of time under such harsh operating conditions and the life of conventional electrodes is naturally rather short.